The purpose of this project is to develop adjunctive hyperthermia modalities for cancer treatment through theoretical and experimental studies of the spatial and temporal variation in the temperature field of tissues subjected to radio-frequency electromagnetic radiation. Currently, we are (1) measuring the patterns of energy deposition produced by a mini-annular phased array (MAPA) applicator within various types of extremity phantoms; (2) describing the electromagnetic fields of a MAPA in terms of its design-parameters; (3) describing the transient thermal profiles within limbs produced by a MAPA; and (4) describing the systemic temperature and cardiac changes associated with heating various regions of the body. We are also developing a non-invasive method for measuring temperature using magnetic resonance imaging. These studies are forming the basis for the clinical system currently being tested under the auspices of a recently approved Phase I clinical protocol.